The present invention relates to magnetic tape cassettes, and more particularly to a magnetic tape cassette in which tape guides closest to a pair of hubs on which a magnetic tape is wound are improved.
In a conventional magnetic tape cassette for audio recording, the magnetic tape is wound on a pair of hubs and runs along an opening formed in the front of the cassette. The tape is laid in the cassette to run while being guided by guide rollers provided at both ends of this opening. Guides such as M-shaped ribs and head pins are provided between the guide rollers, and pillar-shaped guides are provided slightly behind the guide rollers and closer to the walls of the cassette.
When the cassette is loaded in the recording and reproducing unit to run the tape, the tape is run by drive power provided at the tape winding side. Therefore, if the tape wound on the hub on the tape winding side is slackened for some reason, the tape running speed abruptly changes. If the tape running speed abruptly changes, a so-called loop forming phenomenon sometimes occurs wherein a tape loop forms between the tape wound on the hub on the tape supplying side and the inner guide. The loop forming phenomenon often results in jamming. That is, if the loop formed is large, the tape may be caught up and wound on the hub on the tape supplying side, as a result of which the running of the tape is soon stopped.
Further, if the tape is wound on the hub displaced significantly in its widthwise direction and is stored for a relatively long time in that state, the tape becomes permanently deformed. If such a tape is used for recording or reproducing, the magnetic surface thereof cannot be brought into sufficient contact with the magnetic head, and accordingly difficulties such as level variations occur.
In view of the foregoing, an object of the invention is to provide a magnetic tape cassette in which the above-described loop forming phenomenon is prevented, and the tape is always wound on the hubs satisfactorily.